Plane polarised light is a special type of light wave where the electric field vector vibrates in only one plane. This plane is always perpendicular to the direction in which the light is traveling. Unlike unpolarised light, which vibrates in all directions, plane polarised light has a specific orientation that makes it useful in many optical applications.
To understand plane polarised light better, let's compare it with unpolarised light. Unpolarised light, like sunlight, has electric field vectors vibrating in all possible directions perpendicular to the direction of propagation. In contrast, plane polarised light has all its electric field vectors aligned in a single plane. This fundamental difference gives polarised light unique properties that are exploited in sunglasses, LCD screens, and many scientific instruments.
The process of creating plane polarised light involves using a polarising filter. When unpolarised light encounters this filter, only the electric field components that are aligned with the filter's transmission axis can pass through. All other components are absorbed or blocked. This selective transmission results in light that vibrates in only one plane, creating plane polarised light. The intensity of the transmitted light is typically reduced to about half of the original intensity.
Plane polarised light has numerous practical applications in our daily lives. Polarised sunglasses use this principle to reduce glare from reflected surfaces like water or roads. LCD screens rely on polarised light to control pixel brightness and create images. Photographers use polarising filters to reduce reflections and enhance contrast in their images. In scientific research, polarised light helps analyze the structure of materials and crystals. Even 3D movies use polarisation to create the illusion of depth by sending different images to each eye.
In summary, plane polarised light is a fundamental concept in optics where the electric field vector vibrates in a single plane perpendicular to the direction of light propagation. This can be mathematically described and is created when unpolarised light passes through a polarising filter. The resulting polarised light has unique properties that make it invaluable in numerous applications, from everyday items like sunglasses and LCD screens to advanced scientific instruments. Understanding plane polarised light is essential for anyone studying optics, physics, or engineering, as it forms the basis for many modern technologies that we rely on daily.